The invention relates to bags used for shipping bulk materials such as granular materials, powders, liquids, pastes, and other flowable and semi-flowable bulk materials. Specifically, the invention relates to devices and arrangements for evacuating the bags.
In the bulk material shipping industry, where plastic bags in totes, such as plastic totes, are used to ship quantities of liquids, pastes, granular materials, powders, and other flowable and semi-flowable bulk materials, substantial quantities of the bulk material can be left in the bag when the bag has been nearly completely evacuated. This is true even where pumps are connected to the drain ports of the bags, and is especially true of more flow-resistant bulk materials, such as drywall paste and mayonnaise. This problem with bulk material shipper bags is created when the bag is evacuated and collapses, which leaves folds of bag material in the tote. When the excess folds are on the bottom near the drain, they can be sucked against the drain port, stalling the pump.
To reduce the amount of bulk material wasted by being left in the bag, prior inventors have tried several approaches. One approach is to incline the bottom of the bag toward the drain port by tilting part or all of the base of the shipping container or even tilting the entire shipping container, plastic tote and all. This approach can be complicated and inefficient since it requires mechanical apparatus to tilt the container if it is not done manually. Additionally, since this approach does little, if anything, to hold the bag in place within the rigid container, the bag can slide when the bottom of the container is tilted. The sliding bag can block the drain port, which prevents removal of further bulk material from the bag and can cause pump stalling.
Another approach is to use a special structure in the bag or in the rigid container to squeeze the residual contents out of the bag. In the case of special structures in the bag, one arrangement stiffens the bag near the drain port using battens or other stiffeners that add to the cost of the bag. Another arrangement adds a special chamber to the bag that can be filled with pressurized air to squeeze the contents from the primary chamber. This arrangement requires the addition of material to the bag solely for the purpose of squeezing the contents of the primary chamber, which increases cost and complexity of manufacture and is inelegant. Additionally, there is no way to prevent pump stalling by excess folds of bag material from blocking the drain port at low bulk material levels. Squeezing the bulk material from the bag in this manner also requires relatively high pressure. To resist the high pressure, reinforced bag material or external pressure-resistant containers must be used that are more expensive than conventional bags and containers.
In the case of special structures in the rigid container, prior inventors have used piston arrangements, rollers, and other external squeezing arrangements. A more passive special rigid container is the pressure-resistant container discussed above. These clearly add significant cost and complexity to the rigid container. Though blockage of the drain port by excess bag material is not as prevalent in these arrangements as it is in arrangements using inflatable chambers, neither is there a way to prevent such blockage.
Another technique for reducing blockage of the drain port is to leave the plunging arrow used to puncture the shipper bag through the drain port extended into the bag. When the bag is evacuated, the plunging arrow presents itself as an obstacle to blockage of the drain port. This delays or reduces the amount of blockage, but a significant amount of bulk material is still left in the bag.
Another prior art device, known as an antivacuum device, can be attached to the drain port to reduce and/or delay blockage of the drain port. The antivacuum device is a cylinder that extends into the bag interior from the drain fitment. A plurality of holes are cut in the sides of the cylinder so that bulk material can flow through the holes if the main opening of the cylinder is blocked by folds of bag material. While this does reduce or delay blockage of the drain port and the amount of wasted bulk material, a significant amount of bulk material is left behind. Additionally, the antivacuum device undesirably increases the cost and complexity of bag manufacture.
A disadvantage of all prior attempts to enhance evacuation of shipper bags and reduce wasted bulk material is that they generally require human intervention during evacuation. Prior arrangements cannot simply be hooked up and allowed to operate until all bulk material that can be has been evacuated. Rather, a human attendant must do something during evacuation to initiate the evacuation enhancement.
With the disadvantages of the prior art, there is a need for a simple, inexpensive, and elegant way to enhance shipper bag evacuation. There is also a need for a liquid shipper arrangement that avoids or at least significantly delays sucking of excess bag material against the input of the drain port or other drain means for the bag. An enhanced-evacuation shipper bag that does not require human intervention during evacuation is also needed.
An additional problem with pillow-type shipper bags is that they generally lack a filling conduit or snout that would enhance ease of filling the bags. Typically, pillow bags include fitments in their tops for filling the bags through fill hoses that can be connected to the fitments. This arrangement is meant for users who can pump bulk material into the bag through the fill hoses. However, many users either do not want or cannot pump their bulk material and instead pour their bulk material into bags, such as open-top pillow bags and fitted bags equipped with snouts. Open-top pillow bags tend to be more difficult to close than snout-equipped fitted bags and are more susceptible to contamination, but snout-equipped fitted bags are more expensive than open-top pillow bags. In addition, prior attempts to incorporate snouts into pillow-type bags have failed for one reason or another. Consequently, there is a need for bags that solve the problems associated with shipper bag evacuation as enumerated above and that, optionally, include a snout for easy filling of the bag.
My invention takes advantage of existing shipper bag construction to provide an inflatable chamber that enhances evacuation of shipper bag contents without requiring human intervention during evacuation. In one embodiment, I add an air input port and conduit to the lower half of a pillow bag opposite the drain port. The input port allows inflation of an interply region between two lower plies of the pillow bag using low pressure air. The air input conduit is preferably connected to a source of pressurized air at the outset of evacuation. The interply region inflates as the bulk material is removed from the bag through the drain port. As the interply region inflates, the inner ply or plies rise near the air input port so that the part beneath the bag contents in that area effectively lifts the fluid and becomes an advancing wall. Unlike prior arrangements, however, the advancing wall doesn""t squeeze the bag contents out the drain port. Rather, the advancing wall simply inclines the bottom of the bag a little at a time and raises the level of the bag contents so that the drain port is always completely covered by bulk material. Because the level of the contents is kept above the drain port until very near the end of evacuation, folds of material that collect as the bag collapses float or ride on the surface of the bulk material and do not block the drain port. Additionally, the inner ply is kept taut at all times by the air pressure, pulling the bag material away from the drain port and further preventing or at least significantly delaying drain port blockage. The combination of the drain port and the plumped interply region also holds the bag in place so that it does not slide around in the container if the container is moved.
In another embodiment, I slightly modify the construction of a pillow bag to enhance the performance of the inflatable chamber. Here I use half the initial number of layers of material as in conventional pillow bags, fold them in half to form the upper and lower plies, and bond the non-fold edges of the plies. Depending on particular needs, I can leave the fold unbonded, bond all plies together very near the fold, bond the layers on the fold, or bond one set of plies parallel to the fold at an advantageous location. This adds little to the cost and complexity of manufacture, yet can greatly improve performance of my invention. To enhance performance of this embodiment when it includes a corner drain port, I rotate the bag 45xc2x0 relative to the tote upon insertion of the bag in the tote so that the bond defining the interply regions is parallel to a diagonal of the tote.
An additional optional feature of my invention is the incorporation of an integral filling conduit, which I prefer to call a snout, into evacuation-enhancing pillow-type bags. I have found a way to include a snout on such pillow bags without significantly increasing cost or difficulty of manufacture. When used in my inflatable, evacuation-enhancing pillow bag, I prefer to form seals between the plies of the bag: one along the side(s) of the bag opposite the drain port and one along the side(s) including (and nearest to) the drain port. The seal opposite the drain port is preferably formed at a point on the side of the bag below the snout. The amount of bag material leading to the drain on either side of the seal is preferably substantially equal, though the exact position can vary depending on the particular application. The other seal is at the midpoint of the bag. The air input port is formed just below the seal opposite the drain. The result of this configuration is a minimization of bulk material left in the bag when no more bulk material can be discharged, significantly increasing the amount of bulk material evacuated from the bag, thus saving the user bulk material, time, and money. I take two or more rectangular layers of material and bond their edges into a shape that will yield a bag with a snout, such as a rectangle with the long base of a trapezoid on one side. Flaps of material are left next to the sides of the trapezoid, and I cut these off to facilitate handling and filling of the bag. Alternatively, I can use one or more rectangular layers of material folded in half, then bond their edges along the sides to form the same trapezoid/rectangle shape. In this alternative, the fold lies on the side of the rectangle opposite the long base of the trapezoid and may not need to be sealed, depending on the particular application and the desires of the user. A drain can be included in one side of either variation of the bag to allow discharge of the bag""s contents.
With the sides of the evacuation-enhancing snout bag thus sealed, it is ready for use. As with the other forms of my evacuation-enhancing pillow-type bulk material shipper bags, I position the bag in a rigid container, such as a plastic shipping tote, so that the seams lie at the midpoints of opposing sides of the container. Alternatively, I can position the bag so that the seams lie in the corners of the tote, depending on the particular needs of the user. The position of the seams must be taken into account when making the bag, however, to ensure adequate material for proper sizing of the bag. With the bag positioned as desired, I then attach the snout to a source of bulk material, preferably using a spanner bar, and fill the bag. When the bag is full, I remove the snout from the spanner bar (if used), tie it off, and ship it. My invention thus provides a much less costly snout bag than prior art arrangements.
Another variation of my invention is intended for use with top discharge systems for container bags. In these systems, the container bag is emptied via its open top or an opening in its top rather than by a bottom drain. Numerous methods can be used for this purpose; however, the most common are dip tubes, hoses, or other drain means that rest with their input ends under or on top of the material to be discharged. A suction pump is often used in conjunction with these methods to drain the contents of the bag; however, gravity acting via a siphon can also be used.
Of the methods listed in the preceding paragraph, the dip tube is the most popular. It will generally be inserted straight downward through the open top of the bag, an upper fill port, or some other opening located in the approximate center of the upper bag surface, but can be angled downward so that its input end is close or adjacent to the bottom of the bag at a side or corner of the bag. In this situation, one of the bag configurations previously described could be used to help facilitate removal of bag contents. However, whether a dip tube or some other top discharge method is used, I have discovered that it is beneficial to hold the upper ply of the two bottom plies down in the vicinity of the input end to facilitate the pooling of material in this location and to help avoid clogging of the input end with excess bag material.
Various means can be used to hold the two lower plies together. This can be accomplished via mechanical means, including the use of a properly designed input end for the drain means or other physical structures to press the upper ply down against the lower ply along appropriate junctures. It can also be accomplished by bonding the two plies together via heat seals, adhesives, double-sided adhesive tapes, or other means along the desired junctures. In the usual case, the input end of the drain means being used is positioned so as to evacuate material from the bottom of the bag at a location close to its center. Thus, for most purposes, I have found it advantageous to create junctures between the bottom plies at locations and in a manner calculated to gradually urge the contents of the bag to a central drain area where the input is located as the interply region inflates. This can be done by creating junctures that encourage symmetrical filling of the interply regions at the bottom of the bag beginning at the periphery of the bag and moving gradually inward towards its center as the bag contents are emptied. However, the methods described herein are versatile and can be used in numerous ways to facilitate the top discharge of container bags.
All of my embodiments overcome all the disadvantages of the prior art discussed above. I enhance evacuation of the bags while keeping costs low and achieving a level of elegance of use. An additional benefit is that, when the interply region is substantially fully inflated, a portion of the bag rises out of the rigid container and acts as an indicator that the bag is empty. My bag and system can be used in any system that uses bags in rigid or semi-rigid containers where the bag has an inflatable portion with at least two plies. This includes any bulk material shipping system using, for example, closed-top pillow bags, open-top pillow bags, and fitted bags Typically such bags will be drained via a drain port, dip tube, or other drain means with an input in, at, or near the bottom of the container. I do not employ external bladders, tilting bottoms, stiffening battens, or a pressure-resistant outer container as do prior art devices. Instead, I take advantage of the structure of the bags to form an inflatable air chamber between the plies of the bags using edge and other seals, bonds, or seams, the air chamber extending beneath some or all of the contents of the bag. My invention can be used with liquids, powders, pastes, or any other suitable bulk materials. Additionally, evacuation enhancement occurs automatically as bag contents level decreases so that no human intervention is required between setup and take down of the bag.